Vertical structure of Sb-intercalated quasifreestanding graphene on SiC(0001)

TL;DR

This study investigates the atomic-scale structure of Sb-intercalated quasi-freestanding graphene on SiC(0001), revealing how antimony decouples graphene from the substrate and details its precise atomic arrangement.

Contribution

It provides the first detailed structural characterization of Sb intercalation in graphene on SiC, using advanced x-ray and electron microscopy techniques.

Findings

Sb intercalation decouples graphene from SiC substrate

Sb layer is mono-atomic and flat

Sb is located near the top Si atoms of SiC

Abstract

Using the normal incidence x-ray standing wave technique as well as low energy electron microscopy we have investigated the structure of quasi-freestanding monolayer graphene (QFMLG) obtained by intercalation of antimony under the $\left(6\sqrt{3}\times6\sqrt{3}\right)R30^\circ$ reconstructed graphitized 6H-SiC(0001) surface, also known as zeroth-layer graphene. We found that Sb intercalation decouples the QFMLG well from the substrate. The distance from the QFMLG to the Sb layer almost equals the expected van der Waals bonding distance of C and Sb. The Sb intercalation layer itself is mono-atomic, flat, and located much closer to the substrate, at almost the distance of a covalent Sb-Si bond length. All data is consistent with Sb located on top of the uppermost Si atoms of the SiC bulk.